Shutters of many kinds are used in the industry today to avoid unintended exposure of a surface to radiant flux, either of material, e.g., during a deposition process, or of electromagnetic radiation, such as, e.g., ultraviolet (UV) or infrared (IR) light. Shutters have in the closed position a shield in front of the area that has to be shielded and the shield is in the open position shifted to a position outside the screening area.
Shutters are sometimes used in Physical Vapor Deposition (PVD) processes when not all deposition sources are being used simultaneously. E.g., the TiAl and Ti sources are used in a sequence during deposition of a TiAlN layer followed by a TiN layer. The Ti source is preferably screened by a shutter during TiAlN deposition to avoid a layer of TiAlN being formed on the Ti source, and during the TiN deposition the shutter in front of the Ti source is open, but another shutter is closed in front of the TiAl source.
Another example is a shutter between the detector of an instrument (e.g., an optical spectrometer) and the studied process, e.g., a light source (UV, visible or IR). The shutter avoids unwanted exposure during the time the detector is not measuring.
The most common designs of shutters are schematically shown in FIGS. 1-2. In FIG. 1 there is schematically shown two different side views of a shutter 100 with one axis 102 and a shutter shield 104 mounted close to or at the periphery of the shield. The shutter 100 opens (position A) and closes (position B) by turning (arrow 106) the axis 102 of the shutter 100. The advantages are a robust design and that no extra space is required in front of the deposition source 108, but it requires a lot of space beside the shutter 100 when the shield 104 is in an open position (position A). This limits the number of other parts beside the shutter 100, as, e.g., in a PVD equipment, where sources 108, heater, and viewports are placed in the wall 110 of the PVD recipient.
In FIG. 2 there is shown two different side views of a shutter 120 with two axis 1221, 1222 and two shields 1241, 1242, which are often rectangular as shown in FIG. 2. The shutter 120 opens (position A) and closes (position B) by turning the two axis 1221, 1222 of the shutter 120. The advantages are a robust design, and the space beside the shutter 120 is in the open position (position A) only occupied by the area of the shields 1241, 1242, in contrast to the shutter shown in FIG. 1. It is therefore possible to screen a big rectangular area with less extra space required. In FIG. 2 there is also shown the deposition source 126. The disadvantages are the space that is required in front of the shutter 120 when turning from the closed (position B) to the open position (position A) and the space required in the open position (position A), even though it is less than for the shutter shown in FIG. 1. The space that is required in front of the shutter 120 is critical in some processes, e.g., some PVD processes. This space sets the shorter limit of the distance between the source 126 and the substrate in the PVD equipment, and the deposition rate decreases with increasing distance between the source 126 and the substrate. As is apparent in FIG. 2, where the screening width is denoted w, the open width for each shield 12 is o=w/2 and the critical distance in front of the shutter 120 is a=w/2.
A similar shutter consists of only one side of the shutter 120 shown in FIG. 2, i.e., only one axis, and one shield, but that increases the space required in front of the shutter.
U.S. Pat. No. 6,315,877 describes a PVD equipment. The equipment includes a shutter which moves along the sides of the wall, i.e., perpendicular to the radial and vertical direction of the vacuum chamber. This solution requires no extra space in front of the shutters, only the space of the shields beside the screening area in the open position. It is therefore suitable for screening large rectangular areas. However, the occupied area in the open position is still the same as for the shutter shown in FIG. 1. The equipment to control the shutters in U.S. Pat. No. 6,315,877 is also rather complex and the system is therefore not as robust as the shutters shown in FIG. 1 and/or FIG. 2.